Re: Perching, climbing, roosting was Re: 11th specimen of Archaeopteryx

[Dann Pigdon <dannj@alphalink.com.au>]

On Wed, Nov 9th, 2011 at 9:44 AM, Don Ohmes <d_ohmes@yahoo.com> wrote:

> On 11/8/2011 5:06 PM, Dann Pigdon wrote:
> 
> > If you climbed trees in the Mesozoic for safety, then they would have to 
> > have been 
considerably tall trees.
> 
> Why? If you mean that mega-theropods were combing through the Mesozoic 
> canopy at night searching for 1 kg tidbits -- well, I doubt it.

Sauropods would consider a 1kg tidbit to be a convenient bite-sized snack.

>> If your climbing abilities weren't much to write home about, then hiding 
>> down low and out of
>> sight might have been a better option. Especially if your cursorial 
>> adaptations were better than 
your
>> aerial ones when it came to abandoning your hiding place and making a dash 
>> for it.

> I don't see that -- speaking strategically, a passive glider that can 
> run well should have a much better chance in a high place than it would 
> dragging that long tail and wings through the bushes.

The problem with passive gliding is that it usually takes the subject downward 
as well as across - 
potentially closer towards the ground-based creature that disturbed it. Unless 
of course the glider 
was extremely high up to begin with (as per my original suggestion), in which 
case very few 
ground-based creatures would be able to reach it anyway. Although I can see the 
need to evacuate 
a tree if a large herbivore was attempting to push it over in the manner of 
extant elephants.

If we're talking specifically about Archaeopteryx, then I'm guessing its 
running speed and 
maneuverability on the ground was probably better than its speed and agility in 
the air, at least in 
an emergency situation. The safest option for Archie may have been to run into 
a 
mammal/ornithopod burrrow of sufficient size, amongst a jumble of boulders 
where larger 
predators couldn't easily follow, or into extremely dense undergrowth.

-- 
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Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
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